In this paper, ultrasound-assisted aqueous two-phase extraction (UAATPE) performed via a one-step procedure was applied to extract polysaccharides from Ziziphus Jujuba cv. Muzao. Using an ethanol/ammonium sulfate system as a multiphase solvent, effects of UAATPE on extraction of ZMP, such as solvent-to-material ratio, composition of aqueous two-phase system, and extraction time and temperature, were investigated using response surface methodology on basis of results of single-factor experiment. The final optimal conditions were ATPS composition: 29% ethanol and 15% (NH)SO, extraction time: 38min, extraction temperature: 48°C, solvent-to-material ratio: 30, and microwave power: 70W. Under these conditions, the experimental extraction yield was 8.18%. Chemical analysis revealed that ZMP were composed of rhamnose, arabinose, xylose, mannose, glucose, galactose, and galacturonic acid, at a ratio of 1.46:2.47:2.27:1.12:1.00:1.57:5.40, respectively. The structures were also characterized with UV, FTIR, and SEM. The DPPH and ABTS radical scavenging activities showed ZMP had moderately antioxidant activity.